Disk brake caliper having cage bridge

ABSTRACT

A brake apparatus includes a caliper with two housing members secured together by an E-section cage. The housing members straddle a rotor, so as to be able to urge one or more pistons disposed therein to apply brake pads against the rotor, thereby effectuating a braking force on the rotor. The E-section cage provides support for the housing members and reduces the clam shell effect generated by application of the breaking force.

CLAIM OF PRIORITY

This application is a Continuation in Part of application Ser. No.11/108,425, filed Apr. 18, 2005.

BACKGROUND OF THE INVENTION

This invention relates generally to a vehicular disk brake apparatus andmore particularly to the brake caliper thereof, having a reinforced cagefor reducing load.

In general, a vehicular or automotive brake operates on a hydraulicsystem, in which the depression of a brake pedal causes a plunger in themaster cylinder to push hydraulic fluid to a braking unit at the wheels.A disk brake is one kind of braking unit. In a conventional opposedcaliper disk brake, a fixed caliper straddles a rotor, which is attachedto the wheel. In a floating caliper disk brake, the caliper urges pistonor pistons on one side of the rotor to apply a pad, while at the sametime pushing the caliper housing away from the rotor, drawing theoutboard pad up to the rotor. In either case, when fluid from the mastercylinder is introduced into the caliper, it urges one or more pistons inthe caliper to apply brake pad(s) against the rotor, therebyeffectuating a braking force on the rotor and causing the wheel to slowdown or stop.

A typical caliper is formed in the shape of a clam for straddling therotor. Current designs either utilize a one member housing, or twomember housing, straddling over the top of the rotor and held togetherby bolts. In straddling the rotor, one member is disposed on the inboardside of the rotor and the other member is disposed on the outboard sideof the rotor. The members have piston(s) disposed therein.

A basic problem in calipers of this type is that they are subject tohigh shearing and bending forces, with the load bearing on the bridgesection. When such forces are transmitted through the caliper, they actto spread the caliper apart like a clam, a phenomenon often referred toas the “clam shell” effect. The result is decreased braking efficiency,as some of the force generated by the master cylinder is lost in thespreading of the caliper, and there is also the consequent effect ofincreasing pedal travel, tapered pad wear, spongy pedal and loss ofmodulation.

To minimize this deflection, caliper designs have typically utilizedeither a monoblock or a bolting design. For example, in a monoblockcaliper, the caliper is formed from a solid body with a bridge sectionintegrally joining the inboard and outboard members of the caliperhousing. This type of caliper requires a rather massive bridge sectionto effectively reduce the clam shell effect that causes the caliper toopen at the bottom. A massive bridge is undesirable, however, as it getsin the way of maximizing the rotor diameter.

In a caliper where the members are connected by bolts, as shown in FIG.1, there is still a clam shell effect, resulting in the pad cocking withrespect to the rotor face, which causes an increase in pad drag andwear, and a decrease in braking efficiency. The key stress area of acaliper is typically within the pad boundaries, within the pistons.Although the use of a bolting connection may limit the growth of theouter portion of the caliper, it does nothing to stop the deflectionbelow. In other words, the bottom of the caliper is free to open, andwhen subjected to high pressures will still clamp back down on the rotorcausing the pad to attempt to wedge into the rotor, thereby causingtaper.

For the foregoing reasons, there is a need for a disk brake assemblyhaving a brake caliper that is sufficiently stiff to reduce the clamshell effect.

SUMMARY OF THE INVENTION

The present invention is directed to an improved brake caliper thatsatisfies the need for reducing the clam shell effect. A disk brakeapparatus having the features of the present invention comprises a rotorand a brake caliper for applying braking force to the rotor. The brakecaliper is basically comprised of a first housing member and secondhousing member straddling the rotor, with the first and second housingmembers connected by a bridge. The caliper housing members haveactuating pistons disposed therein, with brake pads associated therewithfor engaging the rotor.

The bridge is generally comprised of a cross member and associatedanchors. For example, in an embodiment as shown in FIG. 3, the bridge isformed in the shape of the letter “C” with a cross member and two anchormembers. As shown in the embodiment, the anchor members are downwardturning arms. This type of bridge is generally referred to as aC-section bridge because of its shape. In this type of bridge, the armscan be integrally formed with respect to the cross member, or they canbe separate members fixedly connected to the cross member.

Further, the bridge can take a variety of form and shape thatincorporates the basic combination of cross member and associatedanchors. As an example, the bridge can be comprised of a cross memberand anchor plates. As another example, the bridge can take the shape ofthe letter “Y” with two anchor arms spread at an angle and joined by avertical member. Moreover, the cross member can take various shape, suchas tubular or, as shown in figure FIG. 3, rectangular.

The bridge, as such, provides structural support for the caliper housingmembers. The caliper housing is commonly made of low tensile strengthmaterials in order to reduce weight, as the weight of the caliper, whichtends to be relatively heavy, can affect the operation and suspension ofthe chassis. However, a low strength caliper will have low load capacityand low structural stiffness. The C-bridge provides structural rigidityby using high tensile strength materials, creating a “bending moment”situation, which improves support to the low strength caliper housingmembers. By using high strength materials only where needed, thestrength of the caliper can be maximized while still minimizing weight.

One key advantage of the present invention to be noted is the use ofhigh tensile strength anchors (i.e. the downward turning arms) inbetween the pistons of the caliper, especially as assembled to thecenter portion of the caliper. The use of high strength downward turningarms allows for a stronger bridge design to reduce deflection.

Structurally, the first and second members each have at least onechannel provided therein respectively for receiving the anchor membersof the bridge, and at least one hole formed therein respectively insubstantial alignment with the channels. The bridge has at least twoholes formed in the anchor members. The bridge anchor members arecapable of fitting flush in the channels of the first and secondmembers, such that the holes in the bridge anchor members coaxiallyalign with the holes in the first and second members. A securing means,such as a bolt, capable of passing through the holes in the first andsecond caliper housing members and engaging the holes in the bridge,acts to secure the first member and second member to the bridge.

In another embodiment of the brake caliper, the first and second membersare secured by a plurality of bridges. Accordingly, the first and secondmembers include a plurality of channels therein for receiving the anchormembers of the bridges and a plurality of holes and securing means forconnected the bridges to the first and second members.

In yet another embodiment of the invention, first and second members ofthe brake caliper do not have channels formed therein. Instead, theoutside face of the bridge abuts the inside face of the first and secondmembers, such that the holes in the bridge coaxially align with theholes the in first and second members. In this embodiment, the bridgeextends into the pad area between the housing members. As such, thebridge could provide additional pad support and retention. This wouldincrease the center rigidity by increasing the cross-section thickness.

An advantage of using a bridge such as the C-section is that it providessuperior rigidity, which correspondingly would require less mastercylinder volume to fill the pistons since deflection in the caliper isreduced.

In a preferred embodiment of the invention as shown in FIG. 5, anE-section cage connects the first and second housing members. Incontrast to a C-section bridge, this type of bridge can be referred toas an E-section cage because of its profile. The E-section cage as shownhas a top rectangular frame that includes two side members joined at themidpoint by a one cross member, with the respective ends of the sidemembers connected by endplates. The profile of the rectangular framewith the two endplates and the midpoint anchor can be described asforming an E-section. At the midpoint of each respective side memberwhere the cross member is connected, each side member is connected to adownward anchor. The two respective downward anchors are not unlike theanchors on the C-section bridge in that each anchor has at least onehole formed therein to be in substantial alignment with correspondingholes on the first and second housing members. Similarly, integral tothe outside face of each respective endplate is a recessed shoulderblock having at least one hole formed therein to be in substantialalignment with corresponding holes on the first and second housingmembers. The center portion of each endplate is cut-out to reduceweight, with the endplate tabbed on the bottom edge as shown.

In the preferred embodiment shown in FIG. 5, the inboard surface of eachrespective housing member is recessed in relation to the raisedshoulders of the housing member. The recessed inboard surfaces of thefirst and second housing members are such that the endplates and anchorson the rectangular frame of the E-section cage fit between the recessedsurfaces when first and second housing members are assembled. When theE-section cage is fitted between the first and second housing members,the recessed shoulder blocks on the endplates fit with the raisedshoulders on the first and second housing members. Securing means, suchas bolts, capable of passing through the holes in the first and secondhousing members and engaging the corresponding holes in the anchors andshoulder blocks of the E-section cage, act to secure the first andsecond housing members to the E-section cage as shown in FIG. 5.

In other contemplated embodiments of the invention, the rectangularframe may include more than two side members or multiple cross members.For example, the rectangular frame may include two side members joinedby two cross members with or without endplates. In yet anotheralternative embodiment, the rectangular frame may include two sidemembers connected by endplates but without a cross member. However, thepreferred embodiment is as shown in FIG. 5.

An advantage of the E-section cage is that it provides even greaterstructural rigidity than the C-section bridge because of the rectangularframe. The shoulder blocks on the rectangular frame allow the first andsecond housing members to be connected at the shoulders in addition tobeing connected at the anchors at the midpoint of the rectangular frame,resulting in greater overall rigidity. Hence, the E-section cage allowsthe mechanical stress to be spread over the body of the cage, with muchof the load taken by the shoulder blocks on the rectangular frame,thereby further reducing deflection in the caliper. The greater rigidityof the cage is achieved without sacrificing efficient heat ventilationbecause of the frame structure and the cut-out in the endplates.

DRAWINGS

FIG. 1 is a perspective view of a prior art brake caliper.

FIG. 2 is a perspective view of a brake caliper according to anembodiment of the invention.

FIG. 3 is a partially exploded perspective view of the break caliperaccording to an embodiment of the invention.

FIG. 4 is a cross-section view of an embodiment of the invention.

FIG. 5 is a partially exploded perspective view of the break caliperaccording to a preferred embodiment of the present invention.

DETAILED DESCRIPTION

An embodiment of a brake caliper is shown in FIGS. 2 and 3. Referring toFIG. 2, the brake caliper 10 has first member 12 and second member 14straddling the rotor (not shown), with first and second members 12, 14connected by a bridge 16. FIG. 2 shows brake caliper 10 with bridge 16connected to first and second members 12, 14. FIG. 3 shows a partiallyexploded view of brake caliper 10 with bridge 16 unconnected to firstand second members 12, 14. It is to be noted that although FIGS. 2 and 3show a C-section bridge 16, the bridge can take a variety of form andshape that incorporate the basic combination of cross member andassociated anchors.

Referring to FIG. 3, C-section bridge 16 is generally comprised of across member 16 a and associated anchor arms 16 b and 16 c. TheC-section bridge 16 has at least one hole 16 d in arm 16 b and at leastone hole 16 e in arm 16 c. The first member 12 has at least one channel18 provided therein for receiving arm 16 b of C-section bridge 16, andat least one hole 20 formed therein in substantial alignment withchannel 18. Likewise, second member 14 also has at least one channel 22provided therein for receiving arm 16 c and also at least one hole 24(as shown in FIG. 4) formed in substantial alignment with channel 22.Referring to FIGS. 3 and 4, the anchor arms 16 b, 16 c of C-sectionbridge 16 are capable of fitting flush in channels 18, 22 of first andsecond members 12, 14, such that holes 16 d, 16 e in C-section bridge 16coaxially align with holes 20, 24 in first and second members 12, 14. Asecuring means 26 passing through holes 20, 24 and engaging holes 16 d,16 e secures first member 12 and second member 14 to C-section bridge16.

First and second members 12, 14 can also be secured by a plurality ofC-section bridges 16. Accordingly, first and second members 12, 14 wouldinclude a plurality of channels 18, 22 therein for receiving anchor arms16 b, 16 c, and a plurality of holes 20, 24 for securing means 26 toconnect C-section bridges 16 to first and second members 12, 14.

In another embodiment of the invention, first and second members 12, 14of brake caliper 10 do not have channels 18, 22 formed therein. Instead,the outside face of C-section bridge 16 abuts the inside face of firstand second members 12, 14, such that holes 16 d, 16 e in C-sectionbridge 16 coaxially align with holes 20, 24 in first and second members12, 14.

The preferred embodiment of the invention is shown in FIG. 5. Referringto FIG. 5, an E-section cage 30 connects the first and second housingmembers 12, 14. In contrast to the C-section bridge 16 shown in FIG. 3,this type of cage can be described as an E-section because of itsprofile. The E-section cage 30 has a top rectangular frame 32 whichincludes two side members 34, 36 joined approximately at the midpoint bya cross member 38. At the midpoint of each respective side member 34, 36where the cross member 38 is connected, each side member 34, 36 isconnected to a downward anchor 40. The two respective downward anchors40 are not unlike the anchors on the C-section bridge 16 in that eachanchor 40 has at least one hole 40 a formed therein to be in substantialalignment with holes 20 on the first and second housing members 12, 14.The respective ends of the side members 34, 36 are connected byendplates 42. It should be noted that the center portion of eachendplate 42 can be cut-out to reduce weight as shown in FIG. 5, with theendplate 42 tabbed on the bottom edge as shown. Integral to the outsideface of each respective endplate 42 is a shoulder block 44 that isrecessed with respect to the side edges of endplate 42. Each shoulderblock 44 has at least one hole 44 a formed therein to be in substantialalignment with holes 44 b on the first and second housing members 12,14.

In the preferred embodiment as shown in FIG. 5, the inboard surface ofeach respective housing member 12, 14 is recessed in relation to theraised shoulders of housing member 12, 14. The recessed inboard surfacesof first and second housing members 12, 14 are such that the endplates42 and anchors 40 on rectangular frame 32 of E-section cage 30 fitbetween the recessed surfaces when first and second housing members 12,14 are assembled. When rectangular frame 32 of E-section cage 30 isfitted between the recessed surfaces of first and second housing members12, 14, the recessed shoulder blocks 44 on endplates 42 fit with theraised surfaces of the shoulders on first and second housing members 12,14. A securing means, such as a bolt, capable of passing through holes20 in first and second housing members 12, 14 and engaging holes 40 a inanchors 40, acts to secure first and second members 12, 14 to E-sectioncage 30. In addition, other securing means, capable of passing throughholes 44 b in first and second housing members 12, 14 and engaging holes44 a in shoulder blocks 44 of E-section cage 30, act to further securefirst and second members 12, 14 to E-section cage 30.

The embodiments described herein demonstrate an improved brake caliperhaving a reinforced cage. This brake caliper design will reduce the clamshell effect. Although the present invention has been described inconsiderable detail with reference to certain preferred versionsthereof, other versions are possible. Therefore, the spirit and scope ofthe appended claims should not be limited to the description of thepreferred versions contained herein.

1. A disk brake assembly including a rotor, a brake caliper for applying braking force to said rotor, said brake caliper having first and second housing members straddling said rotor, said first and second housing members connected by a cage, said cage comprising: a rectangular frame including at least two side members joined by at least one cross member; each said side member integrally connected to at least one anchor; said side members connected by at least one endplate; and each said endplate having a shoulder block integral to the outside face of said endplate.
 2. The brake caliper as recited in claim 1, wherein each said first and second housing member has a recessed inboard surface.
 3. The brake caliper as recited in claim 1, wherein said anchor has at least one hole formed therein to be in substantial alignment with corresponding holes on said first and second housing members.
 4. The brake caliper as recited in claim 1, wherein said shoulder block integral to said endplate has at least one hole formed therein to be in substantial alignment with corresponding holes on said first and second housing members.
 5. The brake caliper as recited in claims 3 and 4, wherein securing means capable of engaging said holes in said anchors and said shoulder blocks via said corresponding holes in said first and second housing members function to secure said first housing member and said second housing member to said cage.
 6. A disk brake assembly including a rotor, a brake caliper for applying braking force to said rotor, said brake caliper having first and second housing members straddling said rotor, said first and second housing members each having a recessed inboard surface and each having holes therein, said first and second housing members connected by a cage, said cage comprising: a rectangular frame including at least two side members joined by at least one cross member; each said side member integrally connected to at least one anchor; each said anchor having at least one hole formed therein to be in substantial alignment with corresponding holes on said first and second housing member; said side members connected by at least one endplate; each said endplate having a shoulder block integral to the outside face of said endplate; and each said shoulder block having at least one hole formed therein to be in substantial alignment with corresponding holes on said first and second housing members; wherein said cage fits between said recessed inboard surfaces of said first and second housing members such that said holes on said anchors and said shoulder blocks are in substantial alignment with corresponding holes on said first and second housing members so as to permit securing means capable of engaging said holes in said anchors and said shoulder blocks via said corresponding holes in said first and second housing members to secure said first housing member and said second housing member to said cage. 